Substrate for use with audio file player

ABSTRACT

A substrate includes at least one visual representation of an audio file and encoded data associated with the at least one audio file. The encoded data can be sensed by a selection device to cause an audio file stored in a computer system to be provided to the selection device from said computer system.

FIELD OF INVENTION

The present invention relates to devices for receiving machine-readableinput and for outputting a human discernable output, usually in the formof audio or visual information. More particularly the invention relatesto an audio player which may be used to scan or sense machine-readablecoded data on a surface and to output audio material in response to thesensed coded data.

CO-PENDING APPLICATIONS

Various methods, systems and apparatus relating to the present inventionare disclosed in the following co-pending applications/granted patentsfiled by the applicant or assignee of the present inventionsimultaneously with the present invention: 09/721,895, 09/721,894,09/722,174, 09/721,896, 09/722,148, 09/722,146, 09/721,861, 6,712,452,09/722,171, 09/721,858, 09/722,142, 09/722,087, 09/722,141, 09/722,175,09/722,147, 09/722,172, 09/721,893, 09/722,088, 09/721,862, 6,530,339,09/721,857, 6,631,897, 09/721,860The disclosures of these co-pending applications are incorporated hereinby cross-reference.

Various methods, systems and apparatus relating to the present inventionare disclosed in the following co-pending applications/granted patentsfiled by the applicant or assignee of the present invention on Oct. 20,2000: 09/693,415, 09/693,219, 09/693,280, 09/693,515, 09/693,705,09/693,647, 09/693,690, 09/693,593, 6,474,888, 6,627,870, 6,724,374,09/696,514, 09/693,301, 6,545,482, 09/693,704, 6,527,365, 6,474,773,6,550,997The disclosures of these co-pending applications are incorporated hereinby reference.

Various methods, systems and apparatus relating to the present inventionare disclosed in the following co-pending applications/granted patentsfiled by the applicant or assignee of the present invention on Sep. 15,2000: 6,679,420, 09/669,599, 09/663,701, 6,720,985,

The disclosures of these co-pending applications are incorporated hereinby reference.

Various methods, systems and apparatus relating to the present inventionare disclosed in the following co-pending applications/granted patentsfiled by the applicant or assignee of the present invention on Jun. 30,2000: 09/609,139, 09/608,970, 6,678,499, 09/607,852, 09/607,656,09/609,132, 09/609,303, 09/610,095, 09/609,596, 09/607,843, 09/607,605,09/608,178, 09/609,553, 09/609,233, 09/609,149, 09/608,022, 09/609,232,09/607,844, 6,457,883, 09/608,920, 09/607,985, 6,398,332, 6,394,573,6,622,923The disclosures of these co-pending applications are incorporated hereinby cross-reference.

Various methods, systems and apparatus relating to the present inventionare disclosed in the following co-pending applications/granted patentsfiled by the applicant or assignee of the present invention on May 23,2000: 09/575,197, 09/575,195, 09/575,159, 09/575,132, 09/575,123,09/575,148, 09/575,130, 09/575,165, 09/575,153, 09/575,118, 09/575,131,09/575,116, 09/575,144, 09/575,139, 09/575,186, 6,681,045, 09/575,191,09/575,145, 09/575,192, 09/575,181, 09/575,193, 09/575,156, 09/575,183,09/575,160, 09/575,150, 09/575,169, 6,644,642, 6,502,614, 6,622,999,6,669,385, 6,549,935, 09/575,187, 09/575,155, 6,591,884, 6,439,706,09/575,196, 09/575,198, 6,290,349, 6,428,155, 09/575,146, 09/575,174,09/575,163, 09/575,168, 09/575,154, 09/575,129, 09/575,124, 09/575,18809/575,189, 09/575,162, 09/575,172, 09/575,170, 09/575,171, 09/575,161,6,428,133, 6,526,658, 6,315,399, 6,338,548, 6,540,319, 6,328,431,6,328,425, 09/575,127, 6,383,833, 6,464,332, 6,390,591, 09/575,152,6,328,417, 6,409,323, 6,281,912, 6,604,810, 6,318,920, 6,488,422,09/575,108, 09/575,109, 09/575,110The disclosures of these co-pending applications are incorporated hereinby cross-reference.

BACKGROUND

Purpose-specific devices such as radios and audio cassette players, aswell as more general-purpose devices such as personal computers andorganizers, can be used to play back audio material such as music. Manyof these devices can also be used to record audio material, such asvoice dictation.

In general, these devices don't provide access to situated audio, e.g.to a music clip associated with a concert poster encountered at a trainstation, or spoken instructions associated with a page in a workshopmanual. Each device must be used to seek out the desired audio materialthrough a virtual space accessible through the device, or the audiomaterial must be brought to the device in a device-compatible physicalformat.

The present invention utilizes methods, systems and devices related to asystem referred to as “netpage”, which is described in our co-pendingapplications listed above.

SUMMARY OF INVENTION

In one broad form the invention provides a hand-held audio player with asensor device capable of sensing coded data. Images including coded dataare sensed by the audio player and decoded. The decoded information istransmitted to a computer system which identifies one or more filesstored on the system associated with the decoded data, using previouslystored association data. The file or files identified are transmitted tothe audio player for immediate playback or later playback under usercontrol, either via a built-in loudspeaker or via headphones or similar.

Accordingly, in one broad form, the invention provides an audio playerfor download and playback of audio files, the audio player including: atleast one sensor device capable of sensing images including coded data;a decoder for extracting data from sensed image data; a transceiver fortransmitting the decoded data to a computer system and for receiving oneor more audio files associated with the decoded data from the computersystem; and at least one audio output device for outputting an audiosignal corresponding to the audio file.

In another broad form the invention provides a method of downloadingfiles, the method including: providing a plurality of files; associatingeach of the plurality with one or more identities; providing a userinterface displaying at least one selection data, the or each selectiondata associated with or encoding at least one identity; selecting the orone of the selection data displayed on or by the user interface with aselection device; determining the identity or identities associated withthe selection data and identifying the file or files associated with theidentity or identities determined from the selection data; anddownloading the file or files so identified to the selection device.

The audio player preferably has a memory and a screen for displayinginformation relating to any files stored in the memory.

The user interface is preferably a piece of paper and preferably theimages including code are invisible, infrared absorptive tags. Otherforms of display are possible, such as a screen or substrates carryingelectronically addressable ink, such as E-Ink produced by E-InkCorporation.

The audio player may communicate with the computer system via wirelessor wired means, or by a combination of both.

The audio player may operate out-of-range of a netpage base station ifit is configured to utilize an embedded mobile telephone transceiver, orif it is itself embedded in a mobile telephone which it is configured tointeroperate with.

Each selection on the user interface may be associated with one or morefiles, for instance, a single track or an “album” of many tracks.

Preferably the audio player has a unique identity encoded in the audioplayer, to enable identification of the audio player and/or a userrequesting downloads. If downloaded files are stored in memory the audioplayer identity may also be stored within or in association with storedfiles. Playback of stored files may be limited to the original audioplayer or audio players owned by the same owner. This validation mayoccur within the audio player or by transmitting information to thecomputer system.

Memory provided for storage of downloaded files may be fixed in theaudio player or removable or some may be fixed and some removable.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a front perspective view from below of an audio playeraccording to a first embodiment of the invention;

FIG. 2 shows a rear perspective view from below of the audio player ofFIG. 1;

FIG. 3 shows a front exploded perspective view from above of the audioplayer;

FIG. 4 shows a plan view from above of the audio player;

FIG. 5 shows an end view of the audio player;

FIG. 6 shows a side view from the right of the audio player;

FIG. 7 shows a cross sectional side view of the audio player taken alongline AA shown in FIG. 4.

FIG. 8 shows a perspective view from below of the PCB of the audioplayer;

FIG. 9 shows an exploded perspective view from below of the PCB of theaudio player;

FIG. 10 shows a perspective view from above of the PCB of the audioplayer;

FIG. 11 shows an exploded rear perspective view from above of the audioplayer;

FIG. 12 shows a plan view of a page for use with the first embodiment;and

FIG. 13 shows a block diagram of the electronic components of the audioplayer.

DETAILED DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

Referring to FIGS. 1 to 11 and 13 there is shown an audio player 10. Theaudio player has a body formed of upper and lower casings 12 and 13 inwhich is located a PCB 14. Mounted on the PCB are an optical sensordevice 16, an alphanumeric display 18, control switches 20, a volumecontrol 15, a speaker 22 and a headphone jack 24. The upper and lowercasings 12 and 13 are held together by screws 17 which pass throughopenings 19 in the upper casing 12, through an aperture 21 in the PCB 14and into bosses 23 in the lower casing, so securing the two casings andthe PCB together. The upper casing has an aperture 25 into which thedisplay 18 and an elastomeric keypad 27 extend. A transparent window 29overlays the display 18 and both the window 29 and the keypad 27 areheld in position by a top cover 31. The cover 31 has an aperture 26 intowhich the window 29 extends, so the top surface of the window is flushwith the top of the cover 31. The cover 31 also extends over the screws17. The cover 31 is preferably affixed to the top casing by adhesive butmay be a snap fit to the top casing. The keypad buttons 28 extendthrough corresponding apertures 33 in the cover.

The optical sensor device 16 includes an image sensor 30, infrared LED31, a light guide 32 and lens 34. The near-infrared LED 31 may bestrobed in synchrony with image capture to prevent motion-blurring ofcaptured (tag) images. The image sensor 30 typically consists of a200×200 pixel CCD or CMOS image sensor with a near-infrared bandpassfilter. The light guide 32 and lens 34 may be integrally formed or maybe separate components. The lens extends out of the body. The free endportion 35 of the light guide 32 is cylindrical and a force sensorcollar 37 is slideably mounted on the cylindrical portion. The collarextends beyond the free end of portion 35 so that when the audio playeris pushed against the surface the collar rather than the lens 34contacts the surface.

The collar 37 extends around and behind the optical device 16 andengages a micro switch 39. The micro switch is biased to an openposition; pushing on the collar against the micro switch 39 overcomesthe biasing means in the switch 39 and closes it. When the force isremoved the biasing means urges the collar outward and opens the switchagain. A separate biasing means may be provided external of the switch39 in addition to the micro switch's own biasing means.

The speaker 22 is located in a circular extension 41 at the top of thebody and the top casing 12 is provided with a series of apertures 43 toallow sound to be transmitted by the speaker 22.

The extension 41 also serves as a battery compartment 45 and this isaccessed by a cover 47 which clips onto the lower casing 13. Power issupplied to the PCB by a rechargeable or disposable battery 44. Thebattery 44 is located in the compartment 45 and engages battery contacts49. The speaker and battery contacts are connected to the PCB by wiresets 51 and 53 respectively.

The PCB includes one or more processor chip 36, a flash memory/buffer38, a DRAM chip 43, a transceiver chip 40, a compressed audio decoder 41and an aerial 42. An audio digital to analogue converter 45 and anamplifier 47 are provided but not shown on the PCB.

The processor unit 81 controls and coordinates the various electroniccomponents of the player. The processor executes software whichmonitors, via the sensor 16, the identity of the underlying page and theposition of the player relative to the page; communicates the identityand position data to a netpage base station via the wireless transceiver40; receives audio clip information and streaming audio data from thebase station via the transceiver 40; displays clip information to thedisplay 18; decompresses streaming audio data to the audio output viathe audio decoder 45; and interprets user input captured via the userinterface buttons 28. The embedded software executed by the processor isstored in the non-volatile memory 38, typically in the form of ROMand/or flash memory. Identity information unique to the player, as wellas communications encryption keys, may also be stored in thenon-volatile memory. During execution the processor utilizes fastervolatile memory, typically in the form of a 64 Mbit (8 Mbyte) dynamicRAM (DRAM) 43.

Assuming high-quality 12:1 compression of MP3-encoded audio data, theplayer's memory 43 can hold 9 minutes of stereo audio. With highercompression ratios or more memory, correspondingly longer clips can beheld. If streaming playback is used by the player, then only a smallaudio buffer is required to eliminate transmission jitter, and asignificantly smaller memory may be used.

The processor unit 81 communicates with the other components via ashared bus 49. The processor, the bus, and any number of othercomponents may be integrated into a single chip. As indicated in theblock diagram, the integrated components may include the digitaltransceiver controller 51, the audio decoder interface 53, and the tagimage sensor interface 55. A parallel interface 57 is interposed betweenthe bus 49 and the buttons 48, display 18, LED 31 and contact switch 39.In a more highly integrated chip, they may also include the audiodecoder, the audio DAC, the tag image sensor, and the memory. The analogradio transceiver is unlikely to be integrated in the same chip, but maybe integrated in the same package.

Since the player incorporates a dedicated audio decoder 41, theprocessor only needs to be powerful enough to control and coordinate theother components. Alternatively, the audio decoder may be omitted, and amore powerful processor can used to decode the compressed audio insoftware.

The transceiver 40 is typically a short-range radio transceiver. It maysupport any of a number of wireless transmission standards, includingBluetooth/IEEE 802.15, IEEE 802.11, HomeRF/SWAP, HIPERLAN, and OpenAir.Bluetooth/IEEE 802.15, IEEE 802.11-1997, HIPERLAN, OpenAir, andHomeRF/SWAP all support transmission rates in the range of 1 to 2Mbit/s. IEEE 802.11b supports transmission rates of 5.5 Mbit/s and 11Mbit/s. HIPERLAN also supports a transmission rate of 24 Mbit/s in analternative mode. Beyond these currently-supported wireless LAN (WLAN)standards, next-generation WLAN standards promise to supporttransmission rates of 100 Mbit/s and beyond.

The player may alternatively be connected to the base station by cable,or may utilize a non-radio-frequency wireless transport, such asinfrared. IEEE 802.11, for example, optionally utilizes an infraredtransport. IrDA also utilizes an infrared transport.

The player may alternatively or additionally contain a mobile telephonetransceiver for longer-range communication with a netpage server via amobile telephone network. If the transceiver supports a third-generation‘always-on’ packet-switched connection, then the player may download orstream audio content at will. If the transceiver only supports acircuit-switched connection, then the player may choose to connect (andpotentially stream audio content) only when it encounters a hyperlink.

If the player incorporates a longer-range transceiver, then it may actas a netpage base station for wireless netpage pens and other netpagesensing devices.

Assuming 12:1 MP3 compression, the receiver must support a data rate of118 Kbit/s. This is clearly well within the minimum capabilities of thevarious wireless transmission standards described above.

The PCB 14 may also be provided with a microphone 55 on its lowersurface and the lower casing 13 is provided with an aperture 57 to allowsound to the microphone. A record switch 59 is provided to activate themicrophone 55, also on the lower surface of the PCB. A record button 61overlays the record switch 59 and is accessible via an aperture 63 inthe lower casing. Preferably the button is flush with the outer surfaceor recessed, so as to prevent accidental activation.

The optical sensor device 16 is a netpage sensor capable of detectinginvisible coded tags, as described in our co-pending patent applicationU.S. Ser. No. 09/575,174. The tags have preferably been printed usinginfrared absorptive inks. The PCB processor chips 36 includes all of thefunctional features of a netpage pen as discussed in our co-pendingapplication U.S. Ser. No. 10/291,572 for decoding sensed tags. Thisdecoded data is passed to the transceiver chip 40 for transmittal viaaerial 42 to a netpage base station, such as a netpage printer or anetpage-enabled mobile telephone as disclosed in our co-pendingapplication U.S. Ser. No. 09/721,892. Handshake and authenticationbetween the base station and the audio player occurs before this occurs.Again reference is made to application U.S. Ser. No. 10/291,512 for afull explanation.

In the present embodiment of the invention a netpage 70 is provided.This page is tiled with invisible netpage tags 78 over some or all ofthe surface. For clarity only some tags are shown. The netpage 70includes a listing 72 of audio files, available for downloading andplaying. The files may be music files, speech files or other audiofiles, such as recordings of animal sounds or any combination of typesof recordings. Each entry preferably has a summary of the entry 74 andmeans for the user to select the entry. This may be a separate selectionbutton 76 or by “hyperlinking” the summary information 74 itself.Hyperlinking may be indicated by underlining of text.

A netpage consists of a printed page (or other surface region) invisiblytagged with references to an online description of the page. The tagsmay be printed on or into the surface of the page, may be in or on asub-layer of the page or may be otherwise incorporated into the page.The online page description is maintained persistently by a netpage pageserver. The page description describes the visible layout and content ofthe page, including text, graphics and images. It also describes theinput elements on the page, including buttons, hyperlinks, and inputfields. The page descriptions of different netpages may sharecomponents, such as an image, although the netpages (and the associatedpage descriptions) are visibly different. The page description for eachnetpage may include references to these common components. A netpageallows markings made with a netpage pen on its surface to besimultaneously captured and processed by the netpage system.

Multiple netpages can share the same page description. However, to allowinput through otherwise identical pages to be distinguished, eachnetpage is assigned a unique page identifier. This page ID hassufficient precision to distinguish between all netpages envisaged to beused in the environment of use. If the environment is small then theprecision need not be as great as where the environment is large.

Each reference to the page description is encoded in a printed tag. Thetag identifies the unique page on which it appears, and therebyindirectly identifies the page description. In the preferred embodimentsthe tag also identifies its own position on the page. Characteristics ofthe tags are described in more detail below.

Tags are printed in infrared-absorptive ink on any substrate which isinfrared-reflective, such as ordinary paper. Near-infrared wavelengthsare invisible to the human eye but are easily sensed by a solid-stateimage sensor with an appropriate filter. A sensor sensitive to therelative wavelength or wavelengths may be used, in which case no filtersare required. Other wavelengths may be used, with appropriate substratesand sensors.

The user selects an entry by “clicking” on the hyperlink or theselection “button” and the sensor detects the tag(s) 78 in its field ofview, decodes the tag(s) and transmits the decoded information to thenetpage system via aerial 42. As an alternative to the collar 37, aseparate selection button may be provided on the audio player to enablea user to select a link. “Clicking” the audio player against an entry or“button” involves pushing the collar 37 against the page 70 so as tocause the micro switch to close and then releasing the pressure,typically within a preset (small) time period. Whilst the micro switchis closed the image sensor device is activated and attempts to sense oneor more of the tags on the page; the sensor is off when the micro switchis open to conserve power.

If the click action fails to successfully acquire and decode a tag imagepreferably the audio player emits an audible tone or message via thespeaker 22.

When a selection has been validly made the audio player mayautomatically initiate audio download or streaming. Alternatively theaudio player may ask for user confirmation, using the display 18 andcontrol buttons 28. An invalid selection may also be notified to theuser via the display 18 or via a dedicated LED (not shown).Communication may be via any netpage base station, such as netpageprinter, or via a netpage enabled mobile telephone (see co-pendingapplication U.S. Ser. No. 09/721,892. The netpage system determines thatthe decoded information equates to a request for a particular audio fileor files and transmits the file(s) to the audio player 10 via the sameor a different path as the request was transmitted.

In the preferred form the audio file or files are downloaded in theirentirety and stored in the audio player's memory 38. The audio file maycomprise one song or track or multiple songs or tracks. Alternatively aheader file may be provided with an index of songs or tracks with eachsong or track stored in a separate file. Preferably the audio file alsoincludes information which identifies the song or track titles, tracknumbers, musicians etc. and this information may be displayed on thedisplay 18.

In use, the user may use the control buttons 28 to select any tracksstored in the memory 38. The processor 36 accesses the relevant portionof the memory, extracts the information, converts the (usually) digitalformat to an analogue format. Audio is routed to the speaker, or, if aplug is present in the stereo headphone socket, to the attachedheadphones or other external audio device. Audio may also be routed towireless headphones via the transceiver, either directly from the basestation or via the player.

Digital audio is usually sampled at 44.1 kHz, i.e. at twice the 22.05kHz upper cutoff frequency of the 25th critical band of human hearing.Slightly higher sampling frequencies, such as 48 kHz, are sometimes usedbecause in reality it is impractical to lowpass filter the audio with asharp cutoff at 22.05 kHz prior to sampling. With typical quantizationof 16 bits per channel, a stereo signal therefore generates 1.41 Mbit/s,and this is consequently the data rate of many common digital audioapplications, including, for example, the audio compact disc (if errorcorrection overhead is ignored).

Because the typical 1.41 Mbit/s digital audio data rate is non-trivial,there is a strong incentive to compress the digital audio signal. Themost successful digital audio compression schemes have a perceptualbasis, i.e. they exploit the frequency-dependence of the threshold ofhuman hearing, and signal-dependent masking, whereby a relatively loudertone can locally raise the threshold curve and thus mask relativelysofter adjacent tones. Audio compression also typically relies ontraditional compression techniques such as entropy-coding. Inmulti-channel audio, inter-channel redundancy is also commonlyexploited. A much fuller discussion of digital audio coding is given inPohlmann, K. C., Principles of Digital Audio, 3rd Edition, McGraw-Hill,1995, the contents of which are incorporated herein by reference.

The MPEG Audio Layer 3 (MP3) standard uses perceptual coding to achieve‘near-CD’ and ‘CD’ quality reproduction at compression ratios of between16:1 and 12:1, i.e. reducing the data rate from 1.41 Mbit/s to between88 kbit/s and 118 Kbit/s.

Audio files may be compressed to reduce their size. Any compressionalgorithm may be used; however, the MP3 compression algorithm is,currently, an effective industry standard and so MP3 compression is usedto enable maximum compatibility. A dedicated MP3 decoder 41 is providedfor this purpose, the audio decoder 41 may be an STMicroelectronicsSTA013 decoder (STMicroelectronics, STA013 MPEG2.5 Layer III SourceDecoder,). The STA013 accepts streaming data via a serial interface andis controlled via an I2C interface. Any of a number of other audioencoding standards may be supported via suitable audio decoders,including Dolby AC-3, and RealNetworks' RealAudio. The processor chip 36may provide MP3 decoding by use of software decoding or hardwaredecoding. Other decoding schemes may be incorporated in the audio playertogether with or instead of MP3 decoding. These may be implemented inhardware or software.

The internal memory 39 is preferably 8 MB in size, enough storage forapproximately 9 minutes average MP3 files. Additional storage may beprovided using user replaceable memory, preferably non volatile solidstate memory. Audio files may be downloaded to such user replaceablememory via the audio player 10 or via a user's personal computer. Whereuser replaceable memory is provided, the memory 39 provided for storageof audio files may also be implemented in user replaceable form, i.e.the audio player itself typically will have no permanent memory forstorage of audio files.

In the preferred implementation the audio player downloads audio files,stores the file in memory and then plays the tracks under user control.Where the files are of significant size, downloading the entire file maytake some time and so “streaming” may be implemented. In “streaming” theaudio file is played as it is received, rather than once it has beenfully downloaded. A file played via “streaming” may still be stored inthe memory 38 for later playback.

The audio player optionally includes a microphone and a record button.It can then be used to record speech input, thus providing another kindof netpage input. Recorded speech input may, for example, be associatedwith a location on a netpage, in the form of an annotation, by clickingat the location with the audio player. Subsequent clicks at the samelocation using an audio player then cause the audio annotation to beplayed back. If the surfaces of physical objects are universallynetpage-enabled, i.e. tagged with unique netpage tags, then audioannotations can be placed almost anywhere. Such audio annotations may beprivate or public. When they are private they may only be played back bytheir author. When they are public they may be played back by anyone.

When incorporating a microphone, the audio player can be configured toact as a wireless telephone under the control of a telephonyapplication. Since the player lacks a user interface for dialingnumbers, numbers can be selected from a netpage in the manner describedin our co-pending application U.S. Ser. No. 09/721,895.

An audio clip may be associated with a netpage in the form of ahyperlink, in which case activation of the hyperlink by the audio playeris ultimately handled by an application whose responsibility it becomesto provide the audio clip to the player. An audio clip may also belogically embedded as an audio clip object in a page description, inwhich case clip activation is ultimately handled by the page serverwhich holds the page description. Any click in the zone of the audioclip object is interpreted by the page server as audio clip activation.In either case the actual audio clip may be stored on a separate remoteserver, which may become involved in the streaming playback or downloadof the audio clip.

The audio player can download an audio clip activated by the user intoits internal memory before making it available for playback, or it canstream the audio clip on demand from the remote server in response tothe user interacting with the player's playback controls.

Some of the audio files downloaded will be commercially produced songsfor which the copyright owners require payment. Since the netpage systemincorporates owner and device authentication, providing payment isrelatively simple.

Audio files may be downloaded upon payment for a limited or infinitenumber of playbacks. Where the audio file is limited to a set number ofplaybacks the file may include a counter which is decremented after eachplayback. One-time “playback” may be implemented by streaming, with codeto prevent recording of the file or by use of a counter with an initialvalue of 1. To prevent piracy, particularly where. removable memory isused, the audio file stored may be modified to include the netpage ID ofthe audio player 10 to which it was originally downloaded. Playback maybe limited to that particular audio player or to playback devices ownedby the owner of the original audio player. This second option mayrequire interaction with the netpage system for authentication.

Payment for each playback may also be implemented each time the file isplayed, rather than by way of a single payment. In this scenario, whenthe file is played, the audio player transmits information to thateffect to the netpage system for debiting of the user's account.Authentication from the netpage system after debiting has occurred maybe required before the audio player commences playback.

The player typically incorporates power management. After a period ofinactivity the player may inactivate the status display. After a longerperiod of inactivity the processor may enter a power-conservingquiescent state. Power management may be coupled with the tag sensormicro-switch, allowing wake-up on page interaction. The player may alsoincorporate an accelerometer for this purpose.

Whilst the invention has been described with reference to the netpagesystem which uses invisible tags, the invention is not limited to thenetpage system or the use of invisible tags. If desired, the inventionmay utilize tags or codes which are visible to the average unaided humaneye, such as bar codes. The tags need not merely encode an identitywhich is then used to look up the relevant files. The tags may encodeinstructions at a higher level. For example a tag may encode aninstruction of “play the track entitled X by the artist Y”. If invisibletags are used they need not be limited to the tags disclosed in relationto the netpage system. Other tagging systems are available and anysuitable tagging system may be used. The invention is not limited to theuse of inks which absorb certain wavelengths or fluoresce certainwavelengths. Magnetic inks, surface modification, including apertures,modification of the structure of the substrate itself all fall withinthe scope of the invention. The systems and methods to link the audioplayer of the present invention and the source of the audio files arenot limited to netpage systems. An audio player may be linked by a cableto a single computer, rather than a network of computers.

The present invention has been described with reference to a preferredembodiment and number of specific alternative embodiments. However, itwill be appreciated by those skilled in the relevant fields that anumber of other embodiments, differing from those specificallydescribed, will also fall within the spirit and scope of the presentinvention. Accordingly, it will be understood that the invention is notintended to be limited to the specific embodiments described in thepresent specification, including documents incorporated bycross-reference as appropriate. The scope of the invention is onlylimited by the attached claims.

1. A substrate including at least one visual representation of an audiofile and encoded data associated with the at least one audio file,wherein the encoded data can be sensed by a selection device to cause anaudio file stored in a computer system to be provided to said selectiondevice from said computer system.
 2. A substrate according to claim 1wherein the encoded data is substantially invisible.
 3. A substrateaccording to claim 1 or 2 wherein the encoded data associated with afile is in the same position on the substrate as the visualrepresentation of the file such that a user can cause the selectiondevice to sense the encoded data by placing the selection device overthe visual representation of the file.
 4. A substrate according to anypreceding claim wherein the encoded data is printed using an infra-redink.
 5. A substrate according to claim 1 wherein the substrate ispaper-like.